Antibacterial activity of oregano essential oils against Streptococcus mutans in vitro and analysis of active components

Abstract

Background Streptococcus mutans (S. mutans) is considered the most relevant bacteria during the transition of the non-pathogenic commensal oral microbial community to plaque biofilms that promote the development of dental caries. Oregano (Origanum vulgare L.), is a universally natural flavoring and its essential oil has been demonstrated to have good antibacterial effects. However, the specific antibacterial mechanism of oregano essential oil (OEO) against S. mutans is still not completely understood. Methods In this work, the composition of two different OEOs was determined by GC‒MS. Disk-diffusion method, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined to assess their antimicrobial effect on S. mutans. The inhibition of acid production, hydrophobicity, biofilm formation and real-time PCR for gtfB/C/D, spaP, gbpB, vicR, relA and brpA mRNA expression by S. mutans were assessed to preliminarily investigate the mechanisms of action. Molecular docking was performed to simulate the interactions with the virulence proteins and active constituents. MTT test using immortalized human keratinocytes cells was also performed to investigate cytotoxicity. Results Compared with the positive drug Penicillin /streptomycin 100X (DIZ: 34.13 ± 0.85 mm, MIC: 0.78125 μL/mL, MBC: 6.25 μL/mL), the essential oils of Origanum vulgare L. (DIZ: 80 mm, MIC: 0.625μL/mL, MBC:2.5μL/mL) and Origanum heracleoticum L. (DIZ: 39.67 ± 0.81 mm, MIC: 0.625μL/mL, MBC: 1.25μL/mL) could also exhibit similar effects to inhibit the acid production and reduce the hydrophobicity and biofilm formation of S. mutans at 1/2-1MIC concentration. And gene expression of gtfB/C/D, spaP, gbpB, vicR and relA were found to be downregulated. Due to the composition of essential oils from different sources being highly variable, through effective network pharmacology analysis, we found that OEOs contained many effective compounds, like carvacrol and its biosynthetic precursors γ-terpinene and p-cymene, which may directly target several virulence proteins of S. mutans. Besides, no toxic effect was instigated by OEOs at 0.1 μL/mL in the immortalized human keratinocytes cells. Conclusion The integrated analysis in the present study suggested that OEO might be a potential antibacterial agent for the prevention of dental caries.

Bioactive Phyto-Compounds with Antimicrobial Effects and AI: Results of a Desk Research Study

“…Streptococcus mutans is a naturally occurring microorganism in the human oral microbiota and its overprevalence is associated with the development of caries. Yuan et al [ 19 ] investigated the antibacterial activity of two different oregano essential oils (OEOs) against S. mutans using in vitro methods (disk diffusion method, minimum inhibitory concentration, and minimum bactericide concentration). The results show that OEOs in a concentration below the MIC suppresses the growth of S. mutans and inhibits its cariogenic activity (evaluated by a glycolytic pH drop assay).…”

Antioxidant and Antibacterial Activity of Mexican Oregano Essential Oil, Extracted from Plants Occurring Naturally in Semiarid Areas and Cultivated in the Field and Greenhouse in Northern Mexico

“…In the history of humankind, natural vegetation has represented an important source of natural products that have been widely used in cosmetics, food, and traditional medicine [ 1 , 2 ]. In recent years, there has been a special focus on the search for compounds in natural products to preserve foods (antioxidant activity (AoA)) and protect them from microorganisms (antimicrobial activity (AmA)) [ 3 , 4 , 5 ].…”

“…Additionally, it is widely used in traditional medicine for a variety of ailments, relying on the extraction of its essential oils (EO), which possess recognized AoA and antibacterial activity (AbA) [ 9 , 10 , 11 ]. In the scientific literature, numerous reports strongly associate the chemical composition of oregano essential oil (OEO) with the antioxidant, antibacterial, antifungal, antiparasitic, and antimicrobial properties in several oregano species, as well as with its commercial applications [ 1 , 3 , 5 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ]. Consequently, given the wide range of reported properties of OEO, it stands as one of the favorite candidates for the natural production of antioxidants and antimicrobials.…”

Сultivation experiment of Origanum vulgare L. in Northern Kazakhstan using nitrogen fertilizer

“…In traditional medicine, O. vulgare L. it is used to treat asthma, diarrhea, colds (Li et al, 2022), headaches, rheumatism, diabetes, cardiovascular and nervous system as well as immune deficiency (Akbari et al, 2022;Singletary et al, 2010;Ulupinar et al, 2022;Sharifi-Rad et al, 2021), it is also used as an antifungal agent (Manohar et al, 2001;Andrade et al, 2023;Al Kamaly et al, 2023;Yue et al, 2023), including agents against bacteria and pests that can lead to food spoilage (Özkan et al, 2017;Yoncheva et al, 2021;Alkan, 2023;Susurluk, 2023), and antibacterial food preservative (Yoncheva et al, 2021). The presence of flavonoids and phenolic acids in O. vulgare L. reduces the risk of chronic and oncological diseases (Gutiérrez-Grijalva et al, 2017;Paknejad et al, 2017;Kryeziu et al, 2022).…”